This study suggests that individuals who self-medicate with cannabis are more likely to be young, and use cannabis to treat a wide range of conditions. The reported reasons for self-medication include the lack of information as well as administrative and medical issues. The patterns of cannabis use were highly variable among the study participants, and more than half reported the use of other medications. Finally, not all participants systematically report their cannabis use to healthcare providers. Collectively, these descriptive data provide a complete picture of self-medication with cannabis that can contribute to understanding the problem. To our knowledge, this is the first study that formally described self-medication with cannabis in the general population post-recreational cannabis legalization in Canada.

The observation that individuals who self-medicate with cannabis are mainly young is consistent with the portrait of cannabis use in the general population (Statistics Canada 2020; Roy and Conus 2020). Our recruitment methods (online survey with a focus on social media) may in part explain this higher representativity of younger individuals in our sample. Moreover, mixed medical and recreational users tended to be older than exclusive medical users in our study (73% of medical + recreational users were ≤ 40 years versus 53% for exclusive medical users). A survey conducted before the legalization of recreational cannabis in Canada showed a similar portrait (mean age was 31.1 years for recreational + medical users versus 40.7 years for exclusive medical users) (Turna et al. 2020). In a recent study that included young US participants (aged 18–25 years) with hazardous cannabis use, older individuals were more likely to self-medicate their pain with cannabis (Wallis et al. 2022). In our survey, the observed similar proportion of men and women is not consistent with previous surveys of cannabis users (Turna et al. 2020; Lucas and Walsh 2017). For example, Turna et al. observed a higher proportion of women (59%) among cannabis users (exclusive medical and mixed users) who were surveyed before cannabis legalization in Canada (Turna et al. 2020). In the US sample of young adults, females were more likely to report self-medication of anxiety with cannabis than males (Wallis et al. 2022). Another US study of HIV patients also observed that women were more likely to use cannabis for self-medication (Greenwald et al. 2021). However, Sexton et al. observed a higher proportion of men (54%) in another US sample (Sexton et al. 2016). In a 2015 study of patients registered with a licensed cannabis producer (i.e., patients who likely received a medical prescription), Lucas et al. also observed a higher proportion of men (73%) in their sample (Lucas and Walsh 2017). Our method of recruitment (advertisement on social media with an emphasis towards women) and the fact that some of the groups who shared our survey were women associations may explain our similar proportion of men and women. The observation that women in our sample more often report exclusive medical use of cannabis than men (59% women vs 37% men) was also observed by Turna et al. (77% vs 22%) (Turna et al. 2020). As opposed to age, where individuals were mainly younger, it is interesting to note that individuals with low, medium, and high income were all relying on cannabis to self-medicate their pathology (44% of our sample had annual income >50,000$). This observation is consistent with previous studies (Turna et al. 2020; Lucas and Walsh 2017). Indeed, 42% of Ontario individuals who reported medical use of cannabis (either self-medication or via a prescription) had annual income > 60,000$ (Turna et al. 2020). In a US sample of cannabis users for medical reasons, 51% had annual income > 40,000 US dollars (Sexton et al. 2016).

The main conditions treated by participants in our sample are similar to those reported in previous surveys of patients seeking cannabis to treat a health condition (Sexton et al. 2016; Turna et al. 2020; Lucas and Walsh 2017). Indeed, Sexton et al. observed in a US sample of medical cannabis authorized and self-medicated subjects that the main conditions treated with cannabis were pain (61%), anxiety (58%), and depression (50%) (Sexton et al. 2016). In a sample of Eastern Canadian students who reported medication with cannabis (with 83% of self-medication), the main reason for use was to treat mental health issues (Smith et al. 2021). The main conditions treated with cannabis in self-medication in a sample of US young adults were anxiety (82%), sleep disorders (79%), depression (59%), and pain (40%). The use of cannabis to treat these conditions is consistent with the suggested pharmacologic effects of cannabis and cannabinoids on pain and mental health in the literature (Whiting et al. 2015; Montero-Oleas et al. 2020). The high number of conditions treated per participant in our study and in general is problematic and suggests that cannabis may be perceived as effective for a wide range of conditions, which is not supported by current literature. More communication is needed to inform patients on the lack of scientific evidence on the efficacy of cannabis for most of the claimed indications, the potential risks, the potential interactions with other drugs, and the necessity of an evaluation and follow-up with a healthcare professional to minimize potential risks.

Regarding patterns of use, the observation that THC concentration >20% was reported by a high proportion of participants (i.e., 32%) is a concern as it may expose users to acute toxic effects as well as to long-term adverse effects of cannabis (Health Canada n.d.). This is particularly a concern as a majority of participants reported using cannabis for longer than 1 year to treat a health condition (74%). The lack of medical assistance may explain this use of high concentrations of THC. In previous studies of patients who self-medicate a health condition with cannabis, proportions of patients who reported the use of products with high doses of THC were also high (Sexton et al. 2016; Turna et al. 2020; Stueber and Cuttler 2022). In a study of students who mostly use cannabis to self-medicate their ADHD symptoms, the use of products with high THC/low CBD was reported by 41% of participants while 24% reported use of high THC/high CBD products (Stueber and Cuttler 2022). The use of products with THC concentration > 20% was reported by 27% of this study’s participants (Stueber and Cuttler 2022). Turna et al. also observed in a Canadian sample that products with high THC concentration were reported to be used by 32% of the study participants, with the highest proportion observed among mixed cannabis users (Turna et al. 2020). In a US study of individuals who self-medicate with cannabis, 45.8% of participants mentioned the “claims of high delta 9-tetrahydrocannabinol (THC) potency” as one of the top factors to select their cannabis products (Sexton et al. 2016).

Consistent with the fact that CBD is usually presented as having therapeutic benefits but has less or no psychoactive effects as compared to THC (Health Canada n.d.; MacCallum and Russo 2018), we observed that exclusive medical users had a preference for CBD-dominant products. This preference for CBD-dominant products was previously observed by Turna et al. (35% of exclusive medical users versus 10% of mixed users reported using products with low THC/high CBD concentration (Turna et al. 2020). In most of the previous studies of self-medication with cannabis, information regarding the doses or ratios of THC and CBD was not provided to allow further comparisons with our data (Wallis et al. 2022; Greenwald et al. 2021; Osborn et al. 2015; Sinclair et al. 2020; Hansen et al. 2020).

As compared to previous studies of medical cannabis users (Sexton et al. 2016; Turna et al. 2020; Lucas and Walsh 2017), smoking was the preferred consumption method in our sample. This chronic smoking of cannabis (a majority of participants reported using cannabis for more than 1 year) could potentially negatively impact their respiratory health (Gates et al. 2014). In a sample of Australian women who use cannabis as a self-management strategy of endometriosis, exclusively smoking was reported by 50% of participants while 24% reported multiple methods of use including smoking (Sinclair et al. 2020).

Regarding the frequency of cannabis use, almost half of our study participants reported a daily use of cannabis (45%) with 36% of exclusive medical cannabis users and 48% of mixed users. This pattern of use was quite similar to finding from other studies. Indeed, Turna et al. observed that 40% of their study participants reported daily use of cannabis with mixed users more often reporting daily use (42%) than exclusive medical users (32%) (Turna et al. 2020). A similar proportion of daily cannabis users (43.7%) was also observed in a previous study of Australian women who use cannabis to self-manage endometriosis (Sinclair et al. 2020).

The barriers to accessing medical cannabis are consistent with those reported in previous studies (Lucas and Walsh 2017; Valencia et al. 2017; Sznitman and Lewis 2018). However, the main reason in these studies was usually the cost (Lucas and Walsh 2017; Valencia et al. 2017; Sznitman and Lewis 2018), while the lack of information and the complexity of the process were more prevalent in our sample. The fact that our sample specifically targeted self-medicated individuals may explain this difference. Interestingly, the high majority of participants in our study (80%) reported that they would be interested to have counseling and advice from a healthcare professional for their cannabis use. This information suggests that policies and interventions implemented to target those patients for safer use of cannabis within the healthcare system would be successful. More specifically, addressing the reported barriers to accessing cannabis through the medical circuit is warranted. Particularly, adding medical cannabis services in ambulatory care and decomplexifying the process to obtain medical cannabis and communication could help to reduce self-medication with cannabis and contribute to patients’ safety. Developing and strengthening the cannabis-related expertise of healthcare professionals is also needed for them to engage in appropriate and reassuring discussions with their patients on cannabis, rather than strict refusal or stigmatization, as reported by some participants in our survey and in previous surveys (Lucas and Walsh 2017; Valencia et al. 2017). This is particularly important to avoid conveying patients towards recreational cannabis sellers or illegal sellers to seek advice to use cannabis for their medical conditions as observed in this survey.

The proportion of individuals not reporting their cannabis use to the healthcare professionals (15%) was much lower than what was observed in a study of Eastern Canadian postsecondary students before the legalization of recreational cannabis (Smith et al. 2021). In this latter study, up to 60% of participants reported not declaring their cannabis use to healthcare professionals. Because cannabis use was prohibited during this study and the fact that the sample was exclusively made of students as opposed to our study that included participants from the general population may explain the observed difference between the two measures. However, it is important to note that 31% of our study participants reported that they sometimes declare their cannabis use, a proportion that may contain individuals who never report.